Objectives of the present research were to determine the influences of types of media, sera, time and hormones on equine oocyte in vitro maturation (IVM). The following types of media and sera were evaluated: Menezo's B2 medium (B2), modified Tissue Culture Medium 199 (TCM), Defined Medium (DM), fetal calf serum (FCS), mare serum collected on the first day of estrus (MS), and mare serum collected on the day of ovulation (MSO). Resultant oocyte maturation was compared with the control: DM with bovine serum albumin (BSA). Effect of culture time (0, 15, and 32 hr) and the following hormones on oocyte IVM were evaluated: none, bovine luteinizing hormone (bLH; 1, 10, 100 micrograms/ml), equine luteinizing hormone (eLH; 100 micrograms/ml), bovine follicle-stimulating hormone (FSH; 5 micrograms/ml), and equine chorionic gonadotropin (eCG; 1 and 100 IU/ml). Cumulus expansion in the media and sera experiments was 50% (DM with BSA), 80% (TCM, B2, and DM with MS or MSO), and 100% (FCS with any medium). The proportion of metaphase II (MII) oocytes was significantly (P less than 0.05) increased the percentage of MII oocytes as compared with 0 hr of culture. Cumulus expansion in the hormone experiments was 80% (none, bLH, and eLH), and 100% (eCG and FSH). Freshly prepared bLH significantly (P less than 0.05) inhibited nuclear maturation of equine oocytes. In summary, 15 hr of culture was sufficient time for equine oocyte IVM and all combinations of medium, serum, and hormone addition were equally effective in achieving IVM except fresh bLH and DM with BSA.

Transmission electron microscopy (TEM) was used to evaluate the fine structure of equine oocytes cultured in vitro. Oocytes obtained by follicular aspiration were cultured for either zero or 15 hr. After treatment oocytes were processed either by light microscopy (nuclear evaluation) or TEM (cytoplasmic evaluation). Those oocytes cultured for 15 hr were incubated in modified TCM 199 with 15% (v/v) mare serum (day of ovulation) at 39 +/- 0.2 degree C. Evaluation using TEM revealed that cortical granules were present in all oocytes. However, zero-time oocytes contained few cortical granules, and these were scattered throughout the cytoplasm, whereas 15 hr oocytes contained numerous cortical granules primarily found in very close proximity to the oolemma. Further ultrastructural analysis of both groups revealed organelle structure similar to that previously described for in vivo matured equine oocytes. Evaluation of nuclear maturity (lacmoid stain) showed that 15 hr of culture resulted in significant numbers of oocytes at metaphase II (8/17; 47%). These data demonstrate that oocytes cultured for 15 hr in modified TCM 199 with 15% mare serum (day of ovulation) are mature with respect to nuclear configuration and cortical granule migration and, therefore, would be appropriate candidates for in vitro fertilization.

Effects of trauma on cell production in the subependymal layer of the rat neocortex The response of the subependymal layer (SEL) of the adult rat neocortex was studied after direct trauma, using X-rays, and indirect trauma, after placing a stab wound in the hemisphere close by, but without injuring, the SEL. The SEL in the injured hemisphere underwent marked hypertrophy and hyperplasia by ten days after injury, but the contralateral SEL was unaffected. It is proposed that hyperplasia of the SEL was brought about by the production of immature glial cells in response to the presence of a mitotic stimulant which had diffused into the SEL from the site of injury. X-irradiation caused 98% reduction in the numbers of dark subependymal cells within 24 hours but their numbers recovered within 10 days. In the experiment involving a combination of direct and indirect trauma, the recovery of dark cell number after irradiation was significantly enhanced in the injured, when compared to the uninjured hemisphere. This result supports the hypothesis that stimulation of mitosis by an anti-chalone-like substance, released after knife wounding, had occurred. This substance is likely to be a constituent of plasma, rather than a breakdown product of damaged brain parenchyma. Endogenous division and/or cellular importation may account for the recovery of the SEL observed in these experiments. Geschichte 124, 543-561 CAMMERMEYER J. (1970) The life history of the microglial cell: a light microscope study. Neuroscience Research 3, 43-129 CAVANAGH J.B. & LEWIS P.D. (1969) Perfusion-fixation, colchicine and mitotic activity in the adult rat brain.

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