Many features of the developing nervous system are visible from external observations of intact human embryos. In this study, a photographic atlas from the 4th to the 7th week after ovulation (Carnegie stages 10-18) is provided. The neural folds began to fuse at stage 10, and the rostral and caudal neuropore were closed during stages 11 and 12, respectively. The three primary divisions of the brain were distinguishable before closing of the neural tube. The five secondary brain vesicles were formed during stages 14-15. The development of the cerebellum and cerebrum were first observed at stages 14 and 15, respectively. The mesencephalic flexure was seen at stage 12, and the cervical flexure and pontine flexure at stage 14. After stages 18-19, it became increasingly difficult to identify detailed features of the brain from the surface. Results from this study will help to correlate the characteristic findings of the developing central nervous system of human embryos from stereomicroscopical and light microscopical observations and to locate the exact parts of the developing human brain for other purposes.
Brain/embryology* ; Embryo/anatomy & histology ; Fetal Development ; Human

OBJECTIVETo study the value of basal antral follicle count (AFC) and age in predicting ovarian response and clinical outcome of in vitro fertilization-embryo transfer (IVF-ET).

METHODSA total of 1319 oocyte retrieval cycles in women with an AFC≤10 and complete IVF/ICSI cycles were analyzed retrospectively. According to the AFC, the patients were divided into groups A, B, and C with AFC≤4, of 5-7, and of 8-10, respectively, and each was further divided into <38 years old group and ≥38 years old group. The oocytes retrieved, ovarian response, implantation rate, cancellations, pregnancy, pregnancy loss, and live births were evaluated.

RESULTSAs the AFC increased, the total gonadotrophin (Gn) dose increased and the follicles aspirated and oocytes retrieved decreased significantly (P<0.001). Patients below 38 years of age had a lower total Gn dose and more follicles aspirated and oocytes retrieved than older patients. An AFC>7 and age≥38 years was associated with significantly lower total Gn dose, greater number of follicles aspirated and oocytes retrieved, and lower pregnancy rate than an AFC≤7 and age<38 years (P<0.05). Bivariate correlation and linear regression analysis identified AFC as the best single predictor of ovarian response in IVF. The pregnancy rate differed significantly between the 3 groups, and older patients (≥38 years) had higher early miscarriage rate.

CONCLUSIONAntral follicle count≤7 or age≥38 years old with AFC≤10 is the suitable threshold of diminished ovarian reserve in controlled ovarian stimulation for infertile women. Combination of AFC and age is the best predictor of ovarian response in IVF. Age has a better predictive value of pregnancy rate than AFC. AFC influences mainly the oocytes quantity, while age also affects oocyte quality.

Adult ; Age Factors ; Embryo Transfer ; Female ; Fertilization in Vitro ; Humans ; Ovarian Follicle ; anatomy & histology ; cytology ; physiology ; Ovulation Induction ; Pregnancy ; Pregnancy Outcome ; Retrospective Studies