bids are invited for scientific products first meiotic division , second meiotic division , changes occuring in primordial follice during 1st half of ovarian cycle , graafian follicle, ovulation, corpus luteum , schematic representation of the three phases of oocyte penetration , schematic representation of a section through a human blastocyst , schematic representation of the events taking place during the first week of human development , schematic representation of the changes taking place in the uterine mucosa correlated with those in the ovary , human blastocyst 13 days , development of the villus , villus at the end of the third week of the development , presomite embryo and the trophoblast at the end of the third week , presomite embryo of a 20 days , human embryo at 22 days , 14 somite embryo app. 25 days , transverse sections the development of the mesodermal germ layer day 17,19, 20,21 days , transverse section through embryo at various stages of development to show the effect of the lateral folding on the entoderm lined cavity , structure of the villi at various stages of development , relation of the fetal membranes the wall of the uterus , full term placenta , derivatives of the germ layer , development of the fetal membranes and placenta , development of spinal cord positional changes , various types of spina bifida , formation of the trilaminar germ disc third week of development , development of the limb buds at 5,6,8 weeks , transverse section through a 4 week embryo showing cell of myotome migration of cells of mytome , transverse sections through embryos at various stages of development to show the 1 40various stages of development to show the 7weeks, new born , relationship of hindgut and cloaca at the end of 5th weeks , division of the cloaca into the urogenital sinus and anorectal canal at the end of 5 week, 7 week 8 week , development of the urogenital sinus into the urinary bladder , relationship of the ureters and mesonephric ducts during de