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49-508: The sweet soufflé is made from egg yolk , flour , sugar , and vanilla (or vanilla sugar), mixed into a dough. Next, egg white and granulated sugar are whisked into a meringue until soft peaks form and then mixed into the dough with spatula. Finally, dumplings ( Nocken , diminutive : Nockerl , cf. Gnocchi ) of the mixture are baked in an oven until lightly brown on the outside (10-12 minutes). Salzburger Nockerl are always freshly prepared and served warm with powdered sugar, sometimes with

98-399: A raspberry sauce or any other fruit spread layered on the bottom of the soufflé. Though traditionally a dessert, the dish is filling enough to eat as a main course. Although presumably derived from French soufflé dishes, Salzburger Nockerl, like Kaiserschmarrn or Apple strudel , has become an icon of Austrian cuisine . Legend has it that the dish was invented by Salome Alt (1568–1633),

147-440: A 10% survival rate, but the technique is not yet clinically available. With this technique, cryopreserved ovarian tissue could possibly be used to make oocytes that can directly undergo in vitro fertilization . By definition it means, to recapitulate mammalian oogenesis and producing fertilizable oocytes in vitro.it is a complex process involving several different cell types, precise follicular cell-oocyte reciprocal interactions,

196-453: A G-protein, Gs, also present in the oocyte membrane. Maintenance of meiotic arrest also depends on the presence of a multilayered complex of cells, known as a follicle, that surrounds the oocyte. Removal of the oocyte from the follicle causes meiosis to progress in the oocyte. The cells that comprise the follicle, known as granulosa cells, are connected to each other by proteins known as gap junctions, that allow small molecules to pass between

245-490: A cell competent to further develop when fertilized. It is developed from the primary oocyte by maturation. Oogenesis is initiated in the embryonic stage. In mammals , the first part of oogenesis starts in the germinal epithelium , which gives rise to the development of ovarian follicles , the functional unit of the ovary . Oogenesis consists of several sub-processes: oocytogenesis , ootidogenesis , and finally maturation to form an ovum (oogenesis proper). Folliculogenesis

294-462: A cell whose primary function is to divide by the process of meiosis. However, although this process begins at prenatal age, it stops at prophase I . In late fetal life, all oocytes, still primary oocytes, have halted at this stage of development, called the dictyate . After menarche , these cells then continue to develop, although only a few do so every menstrual cycle . Meiosis I of ootidogenesis begins during embryonic development, but halts in

343-440: A consequence of meiosis. In vitro maturation ( IVM ) is the technique of letting ovarian follicles mature in vitro . It can potentially be performed before an IVF . In such cases, ovarian hyperstimulation is not essential. Rather, oocytes can mature outside the body prior to IVF. Hence, no (or at least a lower dose of) gonadotropins have to be injected in the body. Immature eggs have been grown until maturation in vitro at

392-557: A result of meiosis I, the primary oocyte has now developed into the secondary oocyte . Immediately after meiosis I, the haploid secondary oocyte initiates meiosis II . However, this process is also halted at the metaphase II stage until fertilization , if such should ever occur. If the egg is not fertilized, it is disintegrated and released ( menstruation ) and the secondary oocyte does not complete meiosis II (and does not become an ovum ). When meiosis II has completed, an ootid and another polar body have now been created. The polar body

441-445: A variety of nutrients and combinations of cytokines, and precise growth factors and hormones depending on the developmental stage. In 2016, two papers published by Morohaku et al. and Hikabe et al. reported in vitro procedures that appear to reproduce efficiently these conditions allowing for the production, completely in a dish, of a relatively large number of oocytes that are fertilizable and capable of giving rise to viable offspring in

490-463: A very long time—months in mice, years in humans. Initially, the arrest is due to lack of sufficient cell cycle proteins to allow meiotic progression. However, as the oocyte grows, these proteins are synthesized, and meiotic arrest becomes dependent on cyclic AMP . The cyclic AMP is generated by the oocyte by adenylyl cyclase in the oocyte membrane. The adenylyl cyclase is kept active by a constitutively active G-protein-coupled receptor known as GPR3 and

539-477: A wide range of colors, ranging from nearly white, through yellow and orange, to practically red, or even olive green, depending on the pigments in their feed. Feeding fowl large amounts of capsicum peppers, for example, tends to result in red or deep orange yolks. This has nothing to do with adding colors such as cochineal to eggs in cooking. All bony fish , some sharks and rays have yolk sacs at some stage of development, with all oviparous fish retaining

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588-405: A woman's life, the others will undergo atresia (degeneration). Two publications have challenged the belief that a finite number of oocytes are set around the time of birth generation in adult mammalian ovaries by putative germ cells in bone marrow and peripheral blood. The renewal of ovarian follicles from germline stem cells (originating from bone marrow and peripheral blood) has been reported in

637-433: Is a separate sub-process that accompanies and supports all three oogenetic sub-processes. Oogonium —(Oocytogenesis)—> Primary Oocyte —(Meiosis I)—> First Polar body (Discarded afterward) + Secondary oocyte —(Meiosis II)—> Second Polar Body (Discarded afterward) + Ovum Oocyte meiosis, important to all animal life cycles yet unlike all other instances of animal cell division, occurs completely without

686-446: Is always maintained, presents four phases: If, instead, there is fertilization, the uterine mucosa is modified to accommodate the fertilized egg, and the secretive phase is maintained. Both polar bodies disintegrate at the end of Meiosis II, leaving only the ootid, which then eventually undergoes maturation into a mature ovum. The function of forming polar bodies is to discard the extra haploid sets of chromosomes that have resulted as

735-402: Is an exception to the rule that generally only one product of female meiosis survives to maturity. In plants , oogenesis occurs inside the female gametophyte via mitosis . In many plants such as bryophytes , ferns , and gymnosperms , egg cells are formed in archegonia . In flowering plants , the female gametophyte has been reduced to an eight-celled embryo sac within the ovule inside

784-401: Is associated with depletion of ovarian reserves leading to menopause, but at a slower rate than in those with such mutations. Since older premenopausal women ordinarily have normal progeny, their capability for meiotic recombinational repair appears to be sufficient to prevent deterioration of their germline despite the reduction in ovarian reserve. DNA damages may arise in the germline during

833-400: Is directly influenced by the makeup of the chicken feed. Egg yolk color is generally more yellow when given a feed containing a large component of yellow, fat-soluble pigments, such as the carotenes in dark green plant material, for example alfalfa . Although much emphasis is put onto the color of the egg yolk, it does not reliably reflect the nutritional value of an egg. For example, some of

882-408: Is small in size. The ovarian cycle is divided into several phases: The uterine cycle occurs parallel to the ovarian cycle and is induced by estrogen and progesterone. The endometrium , formed by a monostratified cylindrical epithelium, with uterine glands (simple tubular), connective with a functional superficial layer (divided into a spongy layer, a compact layer, and a deeper basal layer, which

931-407: Is stored more or less in the form in which the maternal body supplied it, partly as processed by dedicated non-germ tissues in the egg , while part of the biosynthetic processing into its final form happens in the oocyte itself. Apart from animals, other organisms, like algae , especially in the oogamous , can also accumulate resources in their female gametes. In gymnosperms , the remains of

980-443: The calcium , iron , phosphorus , zinc , thiamine , vitamin B 6 , folate , vitamin B 12 , and pantothenic acid of the egg. In addition, yolks cover all of the fat-soluble vitamins: A, D, E, and K in the egg, as well as all of the essential fatty acids . A single yolk from a large egg contains roughly 22 mg of calcium, 66 mg of phosphorus, 9.5 micrograms of selenium , and 19 mg of potassium , according to

1029-428: The diplotene stage of prophase I until puberty. The mouse oocyte in the dictyate (prolonged diplotene) stage actively repairs DNA damage, whereas DNA repair is not detectable in the pre-dictyate ( leptotene , zygotene and pachytene ) stages of meiosis. For those primary oocytes that continue to develop in each menstrual cycle, however, synapsis occurs and tetrads form, enabling chromosomal crossover to occur. As

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1078-446: The germinal disc . As food , the chicken egg yolk is a major source of vitamins and minerals. It contains all of the egg's fat and cholesterol , and nearly half of the protein . If left intact when an egg is fried, the yellow yolk surrounded by a flat blob of egg white creates a distinctive "sunny-side up" form. Mixing the two components together before cooking results in a yellow (from pale yellow to almost orange, depending on

1127-451: The ovary of the flower. Oogenesis occurs within the embryo sac and leads to the formation of a single egg cell per ovule. In ascaris , the oocyte does not even begin meiosis until the sperm touches it, in contrast to mammals, where meiosis is completed in the estrus cycle. In female Drosophila flies, genetic recombination occurs during meiosis . This recombination is associated with formation of DNA double-strand breaks and

1176-400: The vitelline membrane , whose structure is different from a cell membrane . The yolk is mostly extracellular to the oolemma , being not accumulated inside the cytoplasm of the egg cell (as occurs in frogs ), contrary to the claim that the avian ovum (in strict sense) and its yolk are a single giant cell. After the fertilization, the cleavage of the embryo leads to the formation of

1225-423: The 1953 film Die Jungfrau auf dem Dach . Egg yolk Among animals which produce eggs , the yolk ( / ˈ j oʊ k / ; also known as the vitellus ) is the nutrient -bearing portion of the egg whose primary function is to supply food for the development of the embryo . Some types of egg contain no yolk, for example because they are laid in situations where the food supply is sufficient (such as in

1274-587: The USDA. Double-yolk eggs occur when ovulation occurs too rapidly, or when one yolk becomes joined with another yolk. These eggs may be the result of a young hen's reproductive cycle not yet being synchronized. Double-yolked eggs seldom lead to successful hatchlings without human intervention, as the chicks interfere with each other's hatching process and do not survive. Higher-order yolks are rare, though hens are known to occasionally lay even triple-yolk eggs. Eggs without yolks are known as "dwarf" or "wind" eggs, or

1323-532: The aid of spindle -coordinating centrosomes . The creation of oogonia traditionally does not belong to oogenesis proper, but, instead, to the common process of gametogenesis , which, in the female human, begins with the processes of folliculogenesis , oocytogenesis, and ootidogenesis . Oogonia enter meiosis during embryonic development, becoming oocytes. Meiosis begins with DNA replication and meiotic crossing over. It then stops in early prophase. Mammalian oocytes are maintained in meiotic prophase arrest for

1372-409: The aim to optimize the characteristics of ovarian tissue culture systems and to better support the three main phases: 1) activation of primordial follicles; 2) isolation and culture of growing preantral follicles; 3) removal from the follicle environment and maturation of oocyte cumulus complexes. While complete oocyte in vitro development has been achieved in mouse, with the production of live offspring,

1421-420: The archaic term "cock egg". Such an egg is most often a pullet's first effort, produced before her laying mechanism is fully ready. Mature hens rarely lay a yolkless egg, but sometimes a piece of reproductive tissue breaks away and passes down the tube. Such a scrap of tissue may stimulate the egg-producing glands to react as though it were a yolk and wrap it in albumen, membranes, and a shell as it travels through

1470-411: The body of the host of a parasitoid ) or because the embryo develops in the parent's body, which supplies the food, usually through a placenta . Reproductive systems in which the mother's body supplies the embryo directly are said to be matrotrophic ; those in which the embryo is supplied by yolk are said to be lecithotrophic . In many species, such as all birds , and most reptiles and insects ,

1519-438: The breed of hen) mass, as in omelets and scrambled eggs . The yolk makes up about 33% of the liquid weight of the egg; it contains about 60 kilocalories (250 kJ), three times the energy content of the egg white, mostly due to its fat content. All of the fat-soluble vitamins ( A , D , E and K ) are found in the egg yolk. Egg yolk is one of the few foods naturally containing vitamin D. The composition (by weight) of

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1568-432: The cells. The granulosa cells produce a small molecule, cyclic GMP , that diffuses into the oocyte through the gap junctions. In the oocyte, cyclic GMP prevents the breakdown of cyclic AMP by the phosphodiesterase PDE3, and thus maintains meiotic arrest. The cyclic GMP is produced by the guanylyl cyclase NPR2. As follicles grow, they acquire receptors for luteinizing hormone, a pituitary hormone that reinitiates meiosis in

1617-456: The decades long period in humans between early oocytogenesis and the stage of meiosis in which homologous chromosomes are effectively paired ( dictyate stage). It has been suggested that such DNA damages may be removed, in large part, by mechanisms dependent on chromosome pairing, such as homologous recombination. Some algae and the oomycetes produce eggs in oogonia . In the brown alga Fucus , all four egg cells survive oogenesis, which

1666-438: The developing embryo. Phosvitins are one of the most phosphorylated (10%) proteins in nature; the high concentration of phosphate groups provides efficient metal-binding sites in clusters. Lipovitellins are involved in lipid and metal storage, and contain a heterogeneous mixture of about 16% (w/w) noncovalently bound lipid, most being phospholipid. Lipovitellin-1 contains two chains, LV1N and LV1C. Yolks hold more than 90% of

1715-413: The egg tube. This is usually what causes an egg to contain a small particle of grayish tissue instead of a yolk. Since these eggs contain no yolk, and therefore cannot hatch, they were traditionally believed to have been laid by roosters. This type of egg occurs in many varieties of fowl and has been found in chickens, both standard and bantams , guineas , and coturnix quail. The color of an egg yolk

1764-422: The female gametophyte serve also as food supply, and in flowering plants , the endosperm . In avian eggs, the yolk usually is a hue of yellow in color. It is spherical and is suspended in the egg white (known alternatively as albumen or glair/glaire) by one or two spiral bands of tissue called the chalazae . The yolk mass, together with the ovum proper (after fertilization, the embryo ) are enclosed by

1813-691: The goal of obtaining oocytes of sufficient quality to support embryo development has not been completely reached into higher mammals despite decades of effort. BRCA1 and ATM proteins are employed in repair of DNA double-strand break during meiosis . These proteins appear to have a critical role in resisting ovarian aging . However, homologous recombinational repair of DNA double-strand breaks mediated by BRCA1 and ATM weakens with age in oocytes of humans and other species. Women with BRCA1 mutations have lower ovarian reserves and experience earlier menopause than women without these mutations. Even in woman without specific BRCA1 mutations, ovarian aging

1862-497: The male process of spermatogenesis, where gametocytes are continuously created. In other words, primary oocytes reach their maximum development at ~20 weeks of gestational age, when approximately seven million primary oocytes have been created; however, at birth, this number has already been reduced to approximately 1-2 million per ovary. At puberty, the number of oocytes decreases even more to reach about 60,000 to 80,000 per ovary, and only about 500 mature oocytes will be produced during

1911-514: The mistress of Prince-Archbishop Wolf Dietrich Raitenau in the early 17th century. In any case, the golden dumplings represent Salzburg's Baroque atmosphere left by the territorial prince, whose life of dissipation came to an end when his archbishopric was challenged by the Bavarian neighbours. They are supposed to represent the hillsides surrounding the city centre: Gaisberg , Mönchsberg and Kapuzinerberg . The dusting of powdered sugar resembles

1960-475: The most prevalent fatty acids in egg yolk typically is: Egg yolk is a source of lecithin , as well as egg oil, for cosmetic and pharmaceutical applications. Based on weight, egg yolk contains about 9% lecithin. The yellow color is due to lutein and zeaxanthin , which are yellow or orange carotenoids known as xanthophylls . The different yolk's proteins have distinct roles. Phosvitins are important in sequestering calcium , iron , and other cations for

2009-414: The mouse. This technique can be mainly benefited in cancer patients where in today's condition their ovarian tissue is cryopreserved for preservation of fertility. Alternatively to the autologous transplantation, the development of culture systems that support oocyte development from the primordial follicle stage represent a valid strategy to restore fertility. Over time, many studies have been conducted with

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2058-406: The natural pigments that produce a rich yolk color are xanthophylls without much nutritional value, rather than the carotenoids that act as provitamin A in the body. Also, a diet rich in vitamin A itself, but without A-provitamins or xanthophylls, can produce practically colourless yolks that are just as nutritious as any richly colored yolks. Yolks, particularly from free-range eggs, can be of

2107-531: The oocyte and causes ovulation of a fertilizable egg. Luteinizing hormone acts on receptors in the outer layers of granulosa cells of the follicle, causing a decrease in cyclic GMP in the granulosa cells. Because the granulosa cells and oocyte are connected by gap junctions, cyclic GMP also decreases in the oocyte, causing meiosis to resume. Meiosis then proceeds to second metaphase, where it pauses again until fertilization. Luteinizing hormone also stimulates gene expression leading to ovulation. Oogenesis starts with

2156-434: The postnatal mouse ovary. In contrast, DNA clock measurements do not indicate ongoing oogenesis during human females' lifetimes. Thus, further experiments are required to determine the true dynamics of small follicle formation. The succeeding phase of ootidogenesis occurs when the primary oocyte develops into an ootid . This is achieved by the process of meiosis. In fact, a primary oocyte is, by its biological definition,

2205-437: The process of developing primary oocytes, which occurs via the transformation of oogonia into primary [oocyte]s, a process called oocytogenesis . From one single oogonium, only one mature oocyte will rise, with 3 other cells called polar bodies. Oocytogenesis is complete either before or shortly after birth. It is commonly believed that, when oocytogenesis is complete, no additional primary oocytes are created, in contrast to

2254-399: The sac after hatching. Lamniform sharks are ovoviviparous , in that their eggs hatch in utero ; in addition to eating unfertilized eggs, unborn sharks participate in intrauterine- cannibalism : stronger pups consume their weaker womb-mates. Oogenesis Oogenesis ( / ˌ oʊ . ə ˈ dʒ ɛ n ɪ s ɪ s / ) or ovogenesis is the differentiation of the ovum (egg cell) into

2303-559: The snow-covered peaks. Fred Raymond (1900–1954) composed in 1938 an operetta called Saison in Salzburg - Salzburger Nockerln (Season in Salzburg - Salzburger Nockerln). In this composition the sweet dumplings are praised as “ Süß wie die Liebe und zart wie ein Kuss ” (meaning Sweet as love and tender as a kiss in German). The character David Slater reminisces about the dish cooked by his ex-wife in

2352-402: The storage and supply of the other nutrients. For example, in some species the amount of yolk in an egg cell affects the developmental processes that follow fertilization . The yolk is not living cell material like protoplasm , but largely passive material, that is to say deutoplasm . The food material and associated control structures are supplied during oogenesis . Some of the material

2401-447: The yolk takes the form of a special storage organ constructed in the reproductive tract of the mother. In many other animals, especially very small species such as some fish and invertebrates , the yolk material is not in a special organ, but inside the egg cell . As stored food, yolks are often rich in vitamins , minerals , lipids and proteins . The proteins function partly as food in their own right, and partly in regulating

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