Relating normal human cardiac development to the anatomical findings in the congenitally malformed heart.

A proper appreciation of cardiac development can now provide the necessary background to understand the anatomical findings in the congenitally malformed heart. We recently presented an account of human cardiac development based on reconstructions of histological datasets from human embryos aged between 3.5 and 8 weeks subsequent to conception.

The development of the external genitals in female human embryos and foetuses. Part 1: Perineal thick skin, clitoris and labia.

Concomitant with the rupture of the cloacal membrane in the 6th week of development, the intermediate layer of the perineal-skin epithelium thickens. We investigated its distribution and the development of the corresponding subcutaneous compartments in serial sections of female human embryos and foetuses and prepared 3D reconstructions to establish topographic relations. The thick-skin area becomes restricted to the outlets of the genital and intestinal tracts.

The development of the external genitals in female human embryos and foetuses. Part 2: Vaginal vestibule, anal canal, perineal raphe and perineal cutaneous muscles.

Concomitant with the rupture of the cloacal membrane, the perineal skin epithelium thickens (see accompanying article). In this study, we establish in female embryos and foetuses that the thick skin area divides into ventral and dorsal areas at ~14 weeks and gradually becomes restricted to the vaginal vestibule and anal canal thereafter. The dense mesenchymal core of the labia minora, which forms at ~8 weeks, extends dorsally to the anal canal as a midline reinforcement.

Human Cardiac Development.

Many aspects of heart development are topographically complex and require three-dimensional (3D) reconstruction to understand the pertinent morphology. We have recently completed a comprehensive primer of human cardiac development that is based on firsthand segmentation of structures of interest in histological sections. We visualized the hearts of 12 human embryos between their first appearance at 3.

Cardiac development demystified by use of the HDBR atlas.

Much has been learned over the last half century regarding the molecular and genetic changes that take place during cardiac development. As yet, however, these advances have not been translated into knowledge regarding the marked changes that take place in the anatomical arrangements of the different cardiac components. As such, therefore, many aspects of cardiac development are still described on the basis of speculation rather than evidence.