Nutritional Secondary Hyperparathyroidism in the Horse

62 Expcrimcntal Nutritional Secondary I-Jypcrparathyroiclism in the Horse
7'a0/(' /YAY]. Weight increase of upper parathyroid glands in relation to ccllular
hypertrophy
I-lorsc Relative weight Volumetric increase
of parathyroids due to hypertrophy
NSI-I 1 2.14 u C 1.99 x c
NSM 2 5.44 x c 2.37 > C
NSII 3 2.88 / C 2.58 ,-' C
(:olltrol (1 c
There was, therefore, an actual increase in parenchymatous tissue. It
has already been demonstrated that the light chief cells were hyper-
trophic. Wheter or not this hypertrophy alone can explain the enlarge-
ment of the glands must now be considered. Table XXI shows how
many times greater the relative parathyroid weights were in NSH
horses than in the control. The volumetric increase due to hypertrophq
is expressed in the same way. The figures of the volumes were obtained
by multiplying the figure of the nuclear surface by a factor r3/+ ( = r,
the mean radius of the nucleus). Thus Table XXI shows that the hyper-
trophy alone cannot explain the enlargement of the glands. It was
therefore concluded that a hyperplasia of the parathyroid glands was
also present in the NSI-I horses.
f*g. 27. (.ontrol. : 45.
Fiq. 29. NSI-I 1. Alandihlc. Ostcitis tibrosa. Ostcoclasts in Howship's lacunae
(straight arrow) or flattened along the bone. Ostcoblastic apposition on opposite
side of trabccu.lac (untilled arrow). Poorly collagcnized fibrous tissue replacing
rcsorbcd bone. 14 & G. r 120.
F;,y, 30. NSH 1. hlasilla. Osteitis tihrosa. All old bone rcsorhcd. Onc largc
ostcoclast with pyknotic nuclci left (arrow). Vivid ostcoblastic activity with
abundant nontnincr.alizcd ostcoid. Fibrous tissue replacing rcsorhcd bone. I4 ct E,
Y 250.
Downloaded from
vet.sagepub.com by guest on April 14, 2010