Scanning Electron Microscopic Study of the Vascular System in the Hemal Node of the Bovine Cervical Region

Abstract

AbSTRAcT. The vasculature of the hemal node (HN) from the bovine cervical region was investigated using a combination of vascular corrosion casting and scanning electron microscopy. A dense vessel network of capsule was found surrounding the cast of HN parenchyma and had no connection with the subcapsular sinus; these vessels converged and exited the HN via the hilar vein. Within the HN, many anastomoses were found between the capillary networks and the surrounding sinuses in the follicular zone and deep cortex. The sinusoid pathway in the HN was characterized by subcapsular sinuses, which were continuous with the trabecular sinuses and tubular sinuses over the parenchyma, and these sinuses finally entered the medullary veins. In our study, direct communications between cortical capillaries and subcapsular sinuses were identified. This may explain the origin of numerous erythrocytes in the HN sinusoids and help to understand lymphocyte migration of the HN. The hemal node (HN) appears to have a lymphoid structure, in which sinuses filled with erythrocytes are present in place of lymph sinuses. HNs are independent lymphatic organs that exist in various mammalian species and also in some birds [1,4,9,20,24,25]. Gibbes [10] described the presence of HNs in humans for the first time in 1884, and they were named by Robertson [19] in 1890. Since then, contradictory views have been held about their function and general biological significance [4,9,20,25]. In recent years, some new concepts have been proposed for the function of HNs including erythrophagocytosis, erythropoiesis, platelet formation and immune cell activation [4,5,21]. An understanding of the HN vascular system is essential, because lymphoid tissue in HNs may play an important role in immune function. The technique of vascular corrosion casting (Vcc) combined with scanning electron microscopy (SEM) can provide information on the three-dimensional structure of the HN and make it possible to study the HN vasculature in detail. Since previous studies of the HN vasculature were performed in rats [3], we undertook a study of the HN from the bovine cervical region to define its vascular architecture using a combination of Vcc and SEM.All animal procedures were approved by the Institutional Animal care and Use committee of the University of Miyazaki. Japanese black calves (3-8 months of age, n=10) were obtained from local farms in Miyazaki Prefecture. The HNs (n=30) along the deep cervical artery were collected with surrounding tissue and cannulated with a fine needle after isolation of the ascending arteriole under a stereomicroscope. The HNs were injected according to the previous reports [3,18]. Briefly, after flushing with warm heparinized saline, 2-3 ml resin (Mercox II Kit, Ladd Research, Williston, VT, U.S.A.) was injected into the HN slowly using a disposable syringe. For polymerization of the resin, the HN with some surrounding tissue was immersed in hot water (60°c) for at least 15 min immediately after resin injection. All tissue surrounding the resin...

Zoological terms in the human histological nomenclature Terminologia Histologica. What we think, what we know, and what we think we know

“…They are capable of performing haematopoietic and immunological functions. These lymphoid organs were described in detail in water buffalos (Zidan and Pabst 2010), cattle (Cerutti et al 1998;Zhang et al 2013), goats (Bozkurt et al 2018), dromedary camels (Zidan and Pabst 2004), pigs (Doboszyńska 2002;Akaydin and Kabak 2006), domestic yaks (Huang et al 2019), roe deer (Akaydın Bozkurt et al 2018) or rats (Castenholz and Castenholz 1996). In spite of that, these organs are in general not known to many immunologists, they are not mentioned in most immunological textbooks, and their presence in humans is controversial until today.…”

“…Ezeasor et al (1989) described the process of phagocytosis in haemal lymph nodes in caprine. Nevertheless, even the mechanism by which erythrocytes enter the parenchyma of the haemal node is still controversial (Zhang et al 2013). Haemal lymph nodes and haemal nodes are dark to brown-red, small, bean-shaped or spherical encapsulated organs (2-12 mm in diameter), typically embedded in adipose tissue (Zidan and Pabst 2004).…”

Peculiarities of human pancreatolienal hemolymph node structure and cellular composition.

“…Результаты и их обсуждение Существует несколько предположений относительно того, каким образом эритроциты попадают в синусы лимфоузлов. Некоторые авторы, анализируя сканирующие электронные микрофотографии гемальных узлов быка, предположили наличие открытых капилляров, которые приносят кровь в субкапсулярный синус и непосредственно в лимфоидную ткань коркового вещества ГЛУ [10]. Далее, согласно этой модели, клетки крови собираются из синусов в воротную вену и таким образом покидают ГЛУ.…”