The anatomy of fetal peripheral lymphatic vessels in the head‐and‐neck region: an immunohistochemical study

Abstract

Using D2-40 immunohistochemistry, we assessed the distribution of peripheral lymphatic vessels (LVs) in the head-and-neck region of four midterm fetuses without nuchal edema, two of 10 weeks and two of 15 weeks' gestation. We observed abundant LVs in the subcutaneous layer, especially in and along the facial muscles. In the occipital region, only a few LVs were identified perforating the back muscles. The parotid and thyroid glands were surrounded by LVs, but the sublingual and submandibular glands were not. The numbers of submucosal LVs increased from 10 to 15 weeks' gestation in all of the nasal, oral, pharyngeal, and laryngeal cavities, but not in the palate. The laryngeal submucosa had an extremely high density of LVs. In contrast, we found few LVs along bone and cartilage except for those of the mandible as well as along the pharyngotympanic tube, middle ear, tooth germ, and the cranial nerves and ganglia. Some of these results suggested that cerebrospinal fluid outflow to the head LVs commences after 15 weeks' gestation. The subcutaneous LVs of the head appear to grow from the neck side, whereas initial submucosal LVs likely develop in situ because no communication was evident with other sites during early developmental stages. In addition, CD68-positive macrophages did not accompany the developing LVs.

Expression of the lymphatic marker podoplanin (D2-40) in human fetal eyes

“…So far, its expression in the human fetal eye has only been reported in the conjunctival lymphatics and the optic nerve sheaths in four eyes of 10 and 15 WoG (Cho et al, 2012). Although D2-40 antigen expression was characterized in an 18 week old fetus, the ocular structures were not investigated (Jin et al, 2010b).…”

Transient Expression of Lymphatic Markers in Retrobulbar Intraconal Orbital Vasculature During Fetal Development

“…Others did not observe intraorbital lymph vessels in four 10 to 12 weeks of gestation old fetuses that were serially sectioned. 27 Although, in that study, only podoplanin was used as an immunohistochemical marker and our cases are of more advanced gestational age. The use of multiple markers in the current study may explain the increased likelihood for identification of lymphatic vasculature.…”

Fetal development of the human trapezius and sternocleidomastoid muscles

“…Conversely, because the embryonic lymphatic vessels are thin and weak, vascular dilation was unlikely to cause or facilitate splitting of the muscles. At this site, corresponding to the lateral or occipital triangle of the adult neck, the lymphatic vessels are usually well developed even in mid-term fetuses [ 15 ]. Moreover, the fetal occipital triangle is a major drainage route from the so-called nuchal translucency (a pathologic or nonpathologic accumulation of great amount of lymphatic fluid in the nuchal subcutaneous tissue) to the venous angle [ 16 ].…”