Lusimbo W S, Leighton F A, Wobeser G A
Department of Veterinary Pathology and Canadian Co-operative Wildlife Health Centre, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5B4 Canada.
Anat Rec. 2000 May 1;259(1):25-34. doi: 10.1002/(SICI)1097-0185(20000501)259:1<25::AID-AR3>3.0.CO;2-Y.
The histology and fine structure of the chorioallantoic membrane of the mallard duck (Anas platyrhynchos), and the density of vessels per millimeter of membrane were assessed between days 12 and 24 of incubation. Light and transmission electron microscopy of the chorioallantoic membrane of the mallard duck after various days of incubation was carried out. Blood vessels within the mesoderm were counted per millimeter of membrane by light microscopy (40x). The chorioallantoic membrane had three distinct layers from day 12 to 24 of incubation, the chorionic epithelium, the mesoderm, and the allantoic epithelium. After day 12, chorionic epithelium consisted of two layers of flattened, elongated epithelial cells interfaced by numerous desmosomes, and separated from the underlying mesoderm by a basement membrane. At this stage, the allantoic epithelium consisted of a single layer of flattened, overlapping cells. Blood capillaries were observed in the mesoderm close to the chorionic epithelium on days 12 and 13; by day 14, these capillaries were located within the chorionic epithelium, forming a capillary sinus. Between days 14 and 16, the chorion underwent cellular and cytological differentiation into three cell types: capillary covering cells, villus cavity cells, and less differentiated basal cells. The mesoderm was composed of a loose matrix of mesenchymal cells and collagen fibrils through which coursed blood and lymphatic vessels. The vascular density in the mesoderm increased rapidly from 4.2+/-0.6 vessels per mm (n = 12) on day 12 to a maximum of 9.4+/-0.3 vessels per mm (n = 15) by day 16. From day 16, the allantoic epithelium had two to three layers of elongated and overlapping cells. The luminal layer of allantoic epithelial cells had microvillus projections and varying numbers of membrane-bound dense vesicles at all stages from day 12 onward. The histologic and ultrastructural features of mallard duck chorioallantoic membrane from day 12 to 24 of incubation were very similar to those described in the chorioallantoic membrane of the chicken (Gallus gallus) from day 8 to 20 of incubation. Much of the information available concerning the CAM of the chicken also may apply to the CAM of the mallard, with timing adjusted to match the developmental time-frame recorded here.
在孵化的第12天至24天之间，对绿头鸭（Anas platyrhynchos）尿囊绒膜的组织学和精细结构以及每毫米膜的血管密度进行了评估。对孵化不同天数后的绿头鸭尿囊绒膜进行了光学显微镜和透射电子显微镜观察。通过光学显微镜（40倍）对中胚层内每毫米膜的血管进行计数。在孵化的第12天至24天，尿囊绒膜有三层不同的结构，即绒毛膜上皮、中胚层和尿囊上皮。12天后，绒毛膜上皮由两层扁平、细长的上皮细胞组成，通过大量桥粒连接，并由基底膜与下方的中胚层分隔。在此阶段，尿囊上皮由单层扁平、重叠的细胞组成。在第12天和13天，在靠近绒毛膜上皮的中胚层中观察到毛细血管；到第14天，这些毛细血管位于绒毛膜上皮内，形成毛细血管窦。在第14天至16天之间，绒毛膜经历细胞和细胞学分化，形成三种细胞类型：毛细血管覆盖细胞、绒毛腔细胞和分化程度较低的基底细胞。中胚层由间充质细胞和胶原纤维的疏松基质组成，血液和淋巴管从中穿过。中胚层的血管密度从第12天的每毫米4.2±0.6条血管（n = 12）迅速增加到第16天的每毫米9.4±0.3条血管（n = 15）的最大值。从第16天起，尿囊上皮有两到三层细长且重叠的细胞。从第12天起的所有阶段，尿囊上皮细胞的腔面层都有微绒毛突起和数量不等的膜结合致密小泡。孵化第12天至24天的绿头鸭尿囊绒膜的组织学和超微结构特征与孵化第8天至20天的鸡（Gallus gallus）尿囊绒膜中描述的特征非常相似。关于鸡尿囊绒膜的许多现有信息也可能适用于绿头鸭的尿囊绒膜，只需调整时间以匹配此处记录的发育时间框架即可。
