The ultrastructure of the in uiuo developed late preimplantation mouse blastocyst has been compared with the fine structure of mouse blastocysts developed in uitro for 72 and 92 hours from the late two-cell stage, as well as those grown in uztro for 26 hours from the late morula or early blastocyst stage. Very little difference was observed between the in uiuo developed blastocysts and those cultured 26 hours in uitro. The differences between 72 and 92 hour-embryos and the in uiuo grown ones were significant. The in uiuo specimen and those grown 26 hours in uitro had differentiated a layer of endoderm cells while the ones cultured in uitro from the two-cell stage did not. Nuclear and cytoplasmic structures in the in uiuo developed blastocysts are well-differentiated while those of the embryos grown in uitro from the two-cell stage were less advanced. Possible reasons for the apparently less differentiated stage of blastocysts developed in uitro from the two-cell stage are discussed.Study of mammalian preimplantation development in vitro has been greatly advanced by Brinster's ('63) formulation of a method which allows two-cell mouse ova to grow to the blastocyst stage in a simple, chemically defined culture medium. Searching for a single source of energy, Brinster ('65) found that pyruvate will support the in vitro development of the largest number of embryos. As a matter of fact, their development (as observed by the light microscope) appears to advance at the same rate in vitro as in vivo (Brinster, '63).Although ultrastructural studies have been completed on in vivo developed preimplantation blastocysts of several species (Enders and Schlafke, '65), and on mouse embryos developed to the morula stage in vitro (Hillman and Tasca, '69) and to the early blastocyst stage in uivo (Calarco and Brown, '69), to our knowledge this is the first study which compares the in vitro developed "late" mouse blastocyst with those grown entirely within the maternal environment. Therefore, the purpose of this investigation was (1) to study in detail the fine structure of "late" preimplantation mouse blastocysts developed in vivo J. EXP. ZOOL., 182: 95-118.for 100 to 108 hours after ovulation, and (2) to compare them with mouse blastocysts of the same post-ovulatory age which had been developed in vitro for 72 hours from the late two-cell stage in Brinster's simple culture medium. MATERIALS AND METHODSSexually mature, random-bred SwissWebster female mice were superovulated with pregnant mare serum (PMS, Gestyl) and human chorionic gonadotropin (HCG, Pregnyl), then mated according to the method of Brinster ('63). Since ovulation in the laboratory mouse occurs 11 to 14 hours after the injection of HCG (Edwards and Gates, '59), the embryonic age of the preimplantation embryos used in this investigation was calculated by estimating the total time which had elapsed since ovulation. At the desired stage of development the specimens were collected and were either (1) fixed immediately or (2) cultured in vitro.In vivo developed lat...

No abstract

Free amino acids and indoles were measured by HPLC in single pineal glands of 5-, 10- and 20-day-old rats sacrificed during mid-light and mid-dark at each age. Melatonin was detectable in neonates (5-day-old), but day vs night differences in indole constituents did not occur until 10 days of age. Free amino acid steady state levels were high in neonates and there was a tendency for reversal of day vs night differences coinciding with the onset of circadian rhythmicity in indole biosynthesis. High correlations (r greater than 0.85) existed for taurine vs. glutamate in individual glands regardless of age and time of sacrifice. These findings suggest that taurine and glutamate are biochemically interrelated and that developmental changes in amino acid metabolic pools reflect functional innervation of the gland.

No abstract