Development of the platysma muscle and the superficial musculoaponeurotic system (human specimens at 8-17 weeks of development).

There is controversy regarding the description of the different regions of the face of the superficial musculoaponeurotic system (SMAS) and its relationship with the superficial mimetic muscles. The purpose of this study is to analyze the development of the platysma muscle and the SMAS in human specimens at 8-17 weeks of development using an optical microscope. Furthermore, we propose to study the relationship of the anlage of the SMAS and the neighbouring superficial mimetic muscles.

Development of the ciliary body: morphological changes in the distal portion of the optic cup in the human.

This study seeks to determine the main events that occur in the development of the ciliary body (CB) in the 5-14th week of development. The CB develops from the distal portion of the optic cup (OC) and the neighboring mesenchyme. During the 5th week of development, 4 zones were observed in the distal portion of the OC: in zone 1, the epithelia of the outer and inner layers of the OC came into contact.

Development of the human tensor veli palatini: specimens measuring 13.6-137 mm greatest length; weeks 6-16 of development.

The present study seeks to determine the main events that occur in the development of the tensor veli palatini (TVP). A light microscope was used on serial sections of 60 human specimens from weeks 6 to 16 of development. The TVP becomes visible in an embryo of 14.

Morphogenesis of the human excretory lacrimal system.

The aim of this study was to determine the principal developmental stages in the formation of the excretory lacrimal system in humans and to establish its morphogenetic period. The study was performed using light microscopy on serial sections of 51 human specimens: 33 embryos and 18 fetuses ranging from 8 to 137 mm crown-rump length (CR; 5-16 weeks of development). Three stages were identified in the morphogenesis of the excretory lacrimal system: (1) the formative stage of the lacrimal lamina (Carnegie stages 16-18); (2) the formative stage of the lacrimal cord (Carnegie stages 19-23); and (3) the maturative stage of the excretory lacrimal system, from the 9th week of development onward.

Morphogenesis of the human lacrimal gland.

The aim of this study was to determine the main stages of the lacrimal gland's developmental process in humans and to establish its precise morphogenetic timetable. Its onset is generally assumed to take place at O'Rahilly's stage 21, arising from an epithelial thickening of the superior extreme of the temporary conjunctival fornix. However, the present study points to a prior stage in the process: the presence of epithelial-mesenchymal changes in embryos at O'Rahilly's stage 19.