Aaron J. Ladman

Silver staining of mitochondria in rat retina as shown by light and electron microscopy.

Mitochondria of the rod terminal spherules localized in the outer plexiform layer of the rats retina, have been selectively stained by the application of the Bodian Protargol method to paraffin and methacrylate sections of retinas fixed in Bensleys acetic-osmicbichromate mixture. In paraffin sections, the silver staining of mitochondria has a sharpness and clarity which surpasses similar sections stained by the anilin-acid fuchsin-methyl green procedure. By means of electron microscopy, particles of silver 0.4 μ in one dimension were seen within the mitochondria. It is thought that in paraffin sections, which are approximately 100 times thicker, these larger particles may be responsible for the observed mitochondrial staining. Smaller particles of silver, 200A to 260A, were deposited on other membranous structures of the rod spherule which include, the synaptic membranes of the rod-bipolar junction, the limiting plasma membranes of the spherule as well as some of the mitochondrial membranes, and the syn...

Effect of Purified Gonadotropins upon Release of Spermatozoa in the Frog, Rana pipiens∗

Summary Release of spermatozoa by the frog, Rana pipiens, after administration of “purified” FSH, LH, prolactin and HCG has been studied. The minimal doses of these hormones which produced a response in over 75% of the animals in each group were: 5 mg of FSH, 0.05 mg of LH and 25 LIT. of HCG. Prolactin did not elicit a response. Our data indicate that the release of spermatozoa in the frog can be induced by LH or a substance with an LH-like activity (HCG). The positive response to FSH is attributed by us to the contamination of the preparation with LH (2 to 3% by manufacturers assay). It is suggested that this rapid and sensitive response to LH might be utilized to assay the purity of FSH preparations.

Bioassay of mouse pituitary gonadotropin by induced ovulation in pregnant mice; evaluation and biologic application.

Summary The ovulatory responses of pregnant mice were evaluated with human chorionic gonadotropin. From these observations the end point response for this material was calculated to be 0.60 I.U. Assays of mouse pituitaries demonstrated a 4-fold decrease in gonadotropin content between parturition and the first postpartum ovulation. This decrease is interpreted as indicating that amounts of pituitary gonadotropin capable of inducing ovulation are released within 3 hours after parturition.