Ultrastructural and morphometric characterization of buffalo (Bubalus bubalis) ovarian preantral follicles

Abstract

The main objective of the present study was to characterize buffalo preantral ovarian follicles. Parts of ovarian cortex, collected from postpubertal buffalo females that were having estrous cycles at regular intervals, were selected under stereomicroscopy and processed for optic and transmission electron microscopy. Primordial follicles were characterized as an oocyte encircled by one layer of flattened cells. The buffalo primordial follicle has a mean diameter of 35 microm and the oocyte diameter is 24.9 microm. The oocyte nucleus is relatively large and eccentric; and in the cytoplasm a large amount of mitochondria, vesicles and endoplasmic reticulum cistern, mainly of the smooth type is observed. The primordial follicles cells are rich in plasma membrane invaginations, which are observed within the cell and between the cell and the oocyte. The primary follicles (mean diameter of 41.8 microm) consist of an oocyte, with a medium diameter of 26.9 microm, surrounded by one layer of cubical granulosa cells. At this follicular stage, the beginning of zona pellucida deposition can also be seen in areas between the oocyte and follicular cells. The secondary follicles, which are surrounded by more than one layer of cubical cells, have a diameter of 53.3 microm, and the oocyte has a mean diameter of 29.4 microm. The ultrastructural analysis showed a large amount of coalescent vesicles, more evident in the oocyte periphery. The zona pellucida (ZP) is thicker at this stage and contains a large quantity of glycoproteins. In general, the ultrastructure of buffalo preantral follicles was similar to that of other mammalian species, but some differences were observed, which indicate species specific characteristics. The main differences observed were cytoplasmic vesicles quantity, mitochondria shape and inner content, ZP deposition and granulosa cell-oocyte junctions. In conclusion, the morphological differences described in this paper, could be responsible for some functional differences observed in Bubalus bubalis in vitro embryo production and follicular dynamics, when compared with Bos taurus or Bos indicus species.

Characterization of folliculogenesis and the occurrence of apoptosis in the development of the bovine fetal ovary

“…In the present study, the average diameter measurements of primordial, primary, and secondary follicles and of oocytes were lower than some of those previously reported [6], although in agreement with those reported in adult cattle [41,42] and adult buffaloes [43]. Though the number of follicular cells in primordial, primary, and secondary follicles was similar to those previously reported in adult cattle [41], it differed from reports in adult buffaloes [43].…”

“…Though the number of follicular cells in primordial, primary, and secondary follicles was similar to those previously reported in adult cattle [41], it differed from reports in adult buffaloes [43].…”

Ultrastructural changes in oocytes during folliculogenesis in domestic mammals

“…In non-domestic cats, the endoplasmic reticulum is not well developed and Golgi complexes are rarely seen [59]. In the ooplasm of buffaloes, a delimited region with a well-developed smooth endoplasmic reticulum is observed [45]. In yaks [52] and pigs [49], polyribosomes are seen on the surface of the rough endoplasmic reticulum and distributed throughout the ooplasm.…”

Follicular Histomorphometry and Evaluation of Ovarian Apoptosis in Queens of Different Age Groups

“…When we compared our findings with the results of other species we observed that the mean follicular diameter was higher in primordial follicles, unilaminar and multilaminar primary follicles (45.13 μm, 70.35 μm and 127.60 μm) than diameters obtained in other species as in pre-pubertal gilts (33.8 μm, 40.4 μm and 84.5 μm) [13] and young women (< 13 years) (39 μm and 44.1 μm) [17]; the mean follicular diameter of older queens was higher in primordial and unilaminar primary follicles (43.24 μm and 68.11 μm, respectively) compared to post-pubertal female buffaloes (7 -10 years) (35 μm and 41.8 μm, respectively) [10]; the mean oocyte diameter in young animals was higher in primordial, unilaminar and multilaminar primary follicles (40.55 μm, 47.97 μm and 62.35 μm, respectively) when comparing with pre-pubertal gilts (26 μm, 27.3 μm and 39.1 μm) [13] and women (< 13 years) with values for primordial and unilaminar primary follicles (34.3 μm and 41 μm, respectively) [17].…”