Paper - On a normal ovum of approximately 9 to 10 days of age (1945)

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Hertig AT. and Rock J. On a normal ovum of approximately 9 to 10 days of age. (1945) Anat. Rec. 91: 281.

Online Editor 
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This historic 1945 abstract from the American Association of Anatomists annual meeting describes early human development in week 2. See also:

Hertig AT. and Rock J. Two human ova of the pre-villous stage, having a developmental age of about seven and nine days respectively. (1945) Contrib. Embryol., Carnegie Inst. Wash. Publ. 557, 31: 65-84.

Hertig AT. and Rock J. On a normal human ovum not over 7.5 days of age. (1945) Anat. Rec. 91: 281.

Hertig AT. and Rock J. On a human blastula recovered from the uterine cavity 4 days after ovulation. (1946) J Gerontol. 1(1): 96-117.

Modern Notes:

Stage 5 Links: Week 2 | Implantation | Lecture | Practical | Carnegie Embryos | Category:Carnegie Stage 5 | Next Stage 6
  Historic Papers: 1941 | 1944 day 9-10 | 1945 day 7.5 | 1945 day 9-10
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Pages where the terms "Historic" (textbooks, papers, people, recommendations) appear on this site, and sections within pages where this disclaimer appears, indicate that the content and scientific understanding are specific to the time of publication. This means that while some scientific descriptions are still accurate, the terminology and interpretation of the developmental mechanisms reflect the understanding at the time of original publication and those of the preceding periods, these terms, interpretations and recommendations may not reflect our current scientific understanding.     (More? Embryology History | Historic Embryology Papers)

On a Normal Ovum of Approximately 9 to 10 days of Age

Arthur T Hertig
Arthur Tremain Hertig (1904-1990)

Arthur T . Hertig and John Rock

Free Hospital for Women, Brookline, Mass., Departments of Pathology, Obstetrics and Gynecology, Harvard Medical School and Department of Embryology, Carnegie Institution of Washington.

Abstract from the 1945 annual meeting of American Association of Anatomists

The ovum (Carnegie Embryo 8215) was discovered in a uterus removed surgically on the fifty-sixth day of the menstrual cycle (periodicity infrequent and irregular). Endometrial histology indicated a typical twenty-fourth day secretory phase with ovulation having occurred approximately 10 days before. The implantation site was posterior, at the corm opposite the ovary of origin, and without visible vascular response. It appeared as a slight elevated area measuring 0.57 mm. in diameter surmounted by a tiny 0.115 X 0.154 mm. area of ulceration.

The chorion measures 0.207 X 0.498 X 0.525 mm.; the chorionic cavity 0.100 X 0.210 X 0.228 mm.; the embryo 0.050 X 0.052 X 0.084 mm. and the amniotic cavity 0.022 X 0.048 X 0.050 mm. The ovum is nearly completely embedded within a rather markedly vascular but relatively ischemic endometrium showing only minimal predecidual response. The trophoblast, indifferent at the abembryonic pole, possesses elsewhere an inner cytotrophoblast and an outer, lacuna-riddled, blood-filled syncytiotrophoblast.

The nearly globular, normally situated, bilaminar germ disk shows early vacuolization of its ectoderm. The amnion is well formed but still lightly attached to its parental trophoblast. Mesoblast formation is active with development of the exocoelomic (Heuser’s) membrane. Angiogenesis is absent within the chorionic cavity. Focal accumulations of cytotrophoblast - primordia of chorionic villi - are beginning to appear.

Cite this page: Hill, M.A. (2020, September 22) Embryology Paper - On a normal ovum of approximately 9 to 10 days of age (1945). Retrieved from

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