I. Ontogeny of the blood and related antigens and their significance for the theory of differentiation

Schechtman, A. M.

doi:10.1515/9781400876778-002

Cited by 19 publications

(8 citation statements)

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“…However, the mechanism by which yolk is synthesized and the site of its synthesis are influenced by several factors, including the location and structure of the ovary and therefore the type of oogenesis (intraovarian or extraovarian), as well as the site of yolk precursor production and(or) storage. Actual yolk synthesis can be carried out within the oocyte, a process called autosynthesis by Schechtman (1955); within cells outside the oocyte, a process termed heterosynthesis by Schechtman (1955); or by a combination of both processes.…”

Section: Routes Of Precursor Entry Into Oocytesmentioning

confidence: 99%

Evolutionary radiation in polychaete ovaries and vitellogenic mechanisms: their possible role in life history patterns

Eckelbarger¹

1983

Can. J. Zool.

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Two types of oogenesis have evolved in polychaetes: one (extraovarian) in which germ cells are ovulated into the coelomic cavity where they undergo vitellogenesis, and another (intraovarian) in which the germ cells are released from the ovary after or near the completion of vitellogenesis. There are many mechanisms of yolk synthesis and significant variation as to the sources of yolk precursors, their route of entry into developing oocytes, and the oocytic organelles involved in yolk synthesis. The evolution of the coelom and its role in nutrient storage and transfer, as well as the origin of germ cells, are intimately related to the evolution of vitellogenic mechanisms in polychaetes. Comparative studies have revealed a correlation between mechanisms of yolk synthesis and the breeding patterns of polychaetes with the rate and type of vitellogenesis being related to the frequency of breeding. Vitellogenic mechanisms in polychaetes are compared with those of other metazoans in an effort to better understand the evolution of this important process and to identify primitive and derived features of yolk synthesis within the Polychaeta.

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Section: Routes Of Precursor Entry Into Oocytesmentioning

confidence: 99%

Evolutionary radiation in polychaete ovaries and vitellogenic mechanisms: their possible role in life history patterns

Eckelbarger¹

1983

Can. J. Zool.

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“…This finding suggests the persistence of micropinocytosis during all phases of segmentation, although at a lower rate than in the two blastomere phase in which the incorporation of "heterosynthetic molecules" (Schechtman 1955) is greater, as shown by Glass (1963) in her work using immunofluorescent techniques. Izquierdo and Vial (1962) and Mazanek (1965) have described the presence of two cytoplasmic zones in the blastomere of the rat.…”

Section: Discussionmentioning

confidence: 81%

Ultrastructural Changes in Preimplantation Rabbit Embryos

Merchant¹

1970

CYTOLOGIA

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“…Oocytes lack both intercellular bridges with follicle cells and any signs of endocytotic activity. Thus yolk is produced by an autonomous mechanism commonly referred to as autosynthesis [12]. This means that yolk globules are synthesized and assembled within the ooplasm, although such synthesis would require that low molecular weight precursors, which ultimately derive from products of digestion occurring in the surrounding gastrodermal cells, enter the oocytes by diffusion or active transport.…”

Section: Yolk Synthesismentioning

confidence: 99%

Ultrastructural study of oogenesis inMonocelis lineata(Turbellaria, Proseriata)

Gremigni

Nigro

1984

International Journal of Invertebrate Reproduction and Developm

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105Oogenesis in the marine turbellarian proseriat Monocelis lineata was investigated at the ultrastructural level. Oocyte differentiation is not synchronous so that successive stages of germ cell maturation were simultaneously detected in each of the two ovaries. Each developing oocyte is enveloped by follicle cell projections which are presumably involved in a morphologically undetectable support of vitellogenesis. The main features evidenced during oocyte differentiation are: (1) The synthesis of cortical granules by the rough endoplasmic reticulum and Golgi complex, occurring in the earlier stages of oogenesis; (2) The synthesis of yolk globules by the rough endoplasmic reticulum (RER) and Golgi complex, occurring in the later stages of oogenesis, namely late meiotic prophase I. Neither morphologically visible endocytotic activity, nor the presence of intercellular bridges, nor even the development of microvilli were observed at the oolemma or cortical ooplasm, so that the sole mechanism of vitellogenesis appears to be autosynthetic. The significance of these findings is discussed in relation to the taxonomic position of M. lineata and more generally in relation to the phylogenetic history of the class Turbellaria.

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I. Ontogeny of the blood and related antigens and their significance for the theory of differentiation

Cited by 19 publications

References 0 publications

Evolutionary radiation in polychaete ovaries and vitellogenic mechanisms: their possible role in life history patterns

Evolutionary radiation in polychaete ovaries and vitellogenic mechanisms: their possible role in life history patterns

Ultrastructural Changes in Preimplantation Rabbit Embryos

Ultrastructural study of oogenesis inMonocelis lineata(Turbellaria, Proseriata)

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