Brenda S. Weakley

Comparison of cytoplasmic lamellae and membranous elements in the oocytes of five mammalian species

SummaryCertain cytoplasmic components of the ovarian oocytes of hamster, rat, mouse, guinea pig and cat are described and compared. Special attention is given to non-membranous cytoplasmic lamellae, concentric arrangements of the endoplasmic reticulum, and the morphology of various membrane-bound bodies. The possible significance of some of these entities is discussed.

Basic protein and ribonucleic acid in the cytoplasm of the ovarian oocyte in the golden hamster

SummaryCytochemical and autoradiographic studies indicate that granular-fibrillar cytoplasmic bodies and intermitochondrial substance in the hamster ovarian oocyte contain both basic protein and ribonucleic acid. The studies suggest that the granular-fibrillar bodies and intermitochondrial substance, although morphologically similar, are not functionally identical. It is proposed that the granular-fibrillar bodies represent stored inactive maternal messenger RNA synthesized during the lampbrush chromosome stage of oogenesis for use in the developing embryo. The function of the intermitochondrial substance is still obscure. The suggestion is put forward that it may represent the synthetic machinery for the manufacture of those mitochondrial proteins for which the mitochondrial DNA is insufficient to code.

Variations in mitochondrial size and ultrastructure during germ cell development.

SummarySize variations and ultrastructural changes in mitochondria of developing germ cells of the female hamster were analyzed. Mitochondria in oogonia of foetus and newborn were elongate with transverse cristae. During pre-dictyate meiotic prophase they became small, rounded, and electron-dense with pleomorphic cristae. These changes were largely reversed when dictyate was reached. Maximum mitochondrial size and complexity of cristae were reached just at the beginning of the phase of rapid oocyte growth, and thereafter declined. As mitochondrial size and number of cristae decreased in the rapidly enlarging oocyte, the ratio of length to width increased, as did electron density of the matrix, until the formation of an antrum within the follicle. After antrum formation, the mitochondria again became more rounded and cristae were seldom seen. An attempt is made to correlate changes of mitochondrial morphology with other events occurring during oogenesis.

Granular cytoplasmic bodies in oocytes of the golden hamster during the post-natal period

SummaryThe time and frequency of occurrence of granular cytoplasmic bodies in oocytes of the golden hamster has been investigated. The bodies are first seen immediately after birth when most of the germ cells have commenced meiotic prophase. They increase in frequency until approximately twelve days post-natal, at which time most oocytes have attained the dictyate stage. After this, frequency of occurrence of the bodies declines. Very few have been noted in adult material. The possible significance of the bodies is discussed.

Balbiani's body in the oocyte of the golden hamster.

SummaryAt a particular stage in the development of the ovarian oocyte in the golden hamster, massive juxtanuclear accumulations of mitochondria grouped in a specific pattern have been observed. This phenomenon is described and its relationship to the “Balbianis body” or “yolk nucleus” of the light microscopists is discussed.

Annulate lamellae in the oocyte of the golden hamster.

SummaryAnnulate lamellae were observed in the cytoplasm of an atretic ovarian oocyte of the golden hamster. This finding is reported because of the rarity of such lamellae in mammalian oocytes (except in the human). Apparent duplications of portions of the nuclear envelope of the same oocyte were also observed. The possible relation of the duplications to the annulate lamellae and to cytoplasmic twin membrane structures characteristic of the hamster oocyte is discussed.

Cytochemistry of the Golgi apparatus in developing ovarian germ cells of the Syrian hamster

SummaryA cytochemical study of the Golgi apparatus in the developing oocyte of the golden hamster was carried out using the TPPase, AcPase and zinc iodide-osmium tetroxide (ZnOs) techniques. Tissue from both immature and sexually mature animals was investigated.Peak TPPase activity was found in pre-growth oocytes in ovaries from sexually mature adults. Some activity was also present in SER in the peripheral cytoplasm of growing oocytes. AcPase activity was found only after the onset of oocyte growth. It was present in Golgi cisternae and associated vesicles and in some profiles of peripheral SER. No structures corresponding to GERL were identified. Strong staining with ZnOs was seen, at all stages studied, in certain Golgi vesicles and short tubules but not in the cisternae unless the oocyte was atretic. Weaker ZnOs staining was characteristic of ER throughout the oocyte.With all techniques there was a falling off of reactivity as oocyte size increased. Within a single oocyte some Golgi bodies were negative while others were positive, with both TPPase and AcPase techniques. This suggests that two or more functional types of this organelle are present within the developing oocytes.

Initial stages in the formation of cytoplasmic lamellae in the hamster oocyte and the identification of associated electron-dense particles.

SummaryThe stage in oocyte development at which cytoplasmic lamellae first appear has been determined and the morphology of the newly formed structures described. An attempt has been made to determine the time of appearance of associated electron-dense particles with respect to the appearance of the lamellae. The electron-dense particles were identified as particulate glycogen by saliva and diastase digestions.

Specializations of the outer mitochondrial membrane during oocyte development

SummaryA coating of electron dense material is present on the cytoplasmic surface of outer mitochondrial membranes in medium-sized hamster oocytes. The coating is not present at earlier or later stages of oocyte development. Its possible relationship to the synthesis and transport of mitochondrial protein is discussed. Associations between endoplasmic reticulum, ribosomes, glycogen and the outer mitochondrial membrane are also described and discussed.

A comparison of three different electron microscopical grade glutaraldehydes used to fix ovarian tissue

‘EM grade’ glutaraldehydes from three suppliers were tested for the following: (1) pH of stock solution, (2) 235/280 nm UV absorbance ratio, (3) milliosmolarity of 2% and 4% solutions, (4) quality of fixation produced in ovarian tissue by fixatives prepared from each stock solution. Low pH of the stock solution appeared to be the most detrimental factor in fixation. Fixatives with a low 235/280 nm ratio (between 0·18 and 0·67) did not give good fixation regardless of the pH of the stock solution. Fixatives made from stock solutions with a pH above 4 and a 235/280 nm ratio between 1 and 2 resulted in the best preservation of ultra‐structure. Variations in milliosmolarity from one batch of stock solution to another were encountered, but appeared to have no correlation with the quality of fixation.; Received 1 October 1973; revision received 20 December 1973